


that moment is a waterfall

by feralphoenix



Category: Undertale (Video Game)
Genre: Alphynecentric, Explicit Sexual Content, F/F, Kink Negotiation, Post-Canon, Spoilers - Undertale Pacifist Route, Xeno
Language: English
Status: Completed
Published: 2017-01-08
Updated: 2017-01-08
Packaged: 2018-09-15 17:52:09
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,142
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9249140
Author URL: https://archiveofourown.org/users/feralphoenix/pseuds/feralphoenix
Summary: In which Alphys and Undyne enjoy the Mew Mew visual novel, among other things.





	

**Author's Note:**

> _(possibilities at sea_ – give my body up to [sunlight](http://marchenwings.tumblr.com/post/154920154999/))
> 
>  
> 
> wrt the xeno tag: since alphys is a monitor lizard and undyne is a fighting fish because Puns Apparently, i based their anatomy loosely on the real-life animals, with a lot of fudging in some aspects to allow for their anthropomorphic bodies.
> 
> alphys' body image issues have a brief mention here or there, if that's not a comfortable topic for you.

You _did_ warn Undyne back when she first started talking about wanting to play the _Mew Mew_ spinoff visual novels that you prefer the original, for-grownups versions, the ones that don’t have the sex scenes censored out. You know she’s not really into erotica with mammalian characters quite the way you are—well, that’s only natural, seeing as she’s never had crushes on mammalian monsters, and so never spent a kind of scandalous amount of time fantasizing about sleeping with one. But. The point is, you didn’t want her to sit through something she wouldn’t want to look at, and it would make you feel bad to have her talk about how your kinks gross her out.

So you talked it out, and she said she would be fine and not to worry, and you felt a lot better, and you’ve been playing the game together happily ever since, but… It feels a little different when you’re _actually playing through a sex scene right now with Undyne watching._

You’re squirming in your seat a little because when you’re alone with these things you, um, sort of tend to set the text advancement to auto so you can, uh, enjoy it more thoroughly?? And it’s been a while since you played the original _Mew Mew_ eroge, so you also forgot how good some of these descriptions were, and…

There’s really no point in beating around the bush, you guess; you really, really want to lift up your skirt and slip a finger or two into yourself, but that’s a little awkward because _Undyne???_ She’s curled up _very close_ around your back with an arm and leg around you, eye bright with interest over your shoulder as you click through Mew Mew and the main character’s first time, the voice actors’ cute little squeaks and moans and the bland BGM playing over your laptop speakers. If you tried to surreptitiously finger yourself now she’d _definitely_ catch you, and you might die on the spot.

Her hand on your stomach is just a few inches too high, too. You try not to squirm too obviously, hoping she won’t notice your claws gone shaky on the keys.

Undyne strokes your side lightly and you nearly die anyway. You _definitely_ make a squeaky whimper that wouldn’t sound so out-of-place playing through your laptop speakers.

“Alphy,” she says right next to your face, grinning.

“Y—yes, Undyne??” you manage somehow.

“You’re cute when you’re trying to hold back and be polite,” she says, grin spreading, “but you don’t _have_ to if you don’t want to when it’s just us.” A pause. “Or d’you want me to do the honors?”

You don’t even try to hold back the moan this time. _“Please.”_

“Okay,” she says, and kisses the side of your neck lightly.

“Um,” you say as her hands start to roam.

“Mm?” She’s busy now tracing patterns up and down your front over top of your clothes, flirting closer to your belly every time. “You can keep clicking, I don’t mind.”

“But—” It’s _extraordinarily_ hard to string together sentences when she’s making your breath hitch this way. The effect that all these little chemical reactions have on your brain is incredible. “You…?”

“May not be my thing so much,” she says, “but _you’re_ really into it and that is _way hot.”_

You gulp and switch the text advancement to auto.

It’s awkward to crane your neck to try to look at Undyne’s face, so you keep your eyes on the screen instead, watching the protagonist describe the sensations of being inside Mew Mew and squirming at the subtle animation of the two lovers moving together. Undyne’s hands send pleasant shivers all over you, but it still takes you off guard when she traces the seam of your cloaca, and you yelp and jolt.

Undyne pulls you a little closer, chuckling. “Too much too soon? Want more of this? Or should I go further?”

“F-further,” you squeak, trying to put strength into your traitor legs so that you can push against her palm.

“Gotcha,” she says, and shifts in her seat for what you guess makes a better angle for her wrist. The next moment she delves right in, spreading her fingers wide to press against your hemiclits, and your legs push out and you sag back against her chest with a groan, your vision going blurry even though your glasses are still set perfectly on your face.

Your moans blend with Mew Mew’s and the hero’s in a way that would have your awkward teen self climaxing in seconds, something right out of your wildest fantasies—you’d always been too self-conscious to make much noise back when it was just you and your hand. Undyne’s long strong fingers feel much better than yours do, though, damp and porous up inside you instead of scaly and stubby. She knows the rhythms you like and stokes your climax steadily, lightly kissing and biting against your round shoulders all the while, her free hand a firm pressure against your lower belly.

On the screen, Mew Mew squeals as she comes, and you whine throaty and wanton as pleasure spikes in you in anticipation. You grip the back of Undyne’s hand to urge her on faster and harder as the hero pulls her fleshy cock out just in time to ejaculate across Mew Mew’s belly and spread thighs, the drops of come lovingly rendered across Mew Mew’s shiny human skin.

Your own orgasm is unsubtle and inelegant as a heat wave, your nasally yell of Undyne’s name about as loud as a foghorn. But Undyne’s fingers fuck you steadily through it, easing off the pressure at _just_ the right moment. (She pays _such close attention_ to your reactions and you’re just completely floored?? _How_ have you managed to somehow get this hot fish lady in your life. Science has yet to find the answer.)

The game has moved on to the postcoital pillow talk scene, which is cute, but you’ve seen it before enough times to remember it, and at this particular moment you’re having fun right where you are, snuggled up with your girlfriend after some very quality one on one time. It takes a minute for you to catch your breath enough to stutter out a “That was really g-good,” but Undyne just grins and slowly withdraws her fingers to wrap her arms around you.

“I knew you were into this,” she says, tone both pleased and thoughtful, “but I didn’t know you were into _this,_ like, specifically. Damn, that’s hot.”

“I-it’s—” You wave your hand, struggling to put words to it all, flushed and energized by Undyne’s curiosity. “There’s just so much _to_ it! L—like, um, o-obviously f… for, um, people built for p-penetrative sex, p-pulling out r-r-red—uh, decreases chances of p-pregnancy, but? Y-you also get to _see_ your p-partner’s orgasm i-instead of just _feeling_ it, s-since apparently d-depending on species and size a-and i-individual sensitivity, a l-lot of people can’t?? A-and then, uhh, ejaculating on your p-partner’s body _specifically_ c-can, can be a marking o-or claiming d-display of d-dominance a-and/or ownership, and it can _also_ b-be a form of sensory play, and…” You realize very abruptly that you’re about to infodump about the deep, revealing psychology of your bukkake kink and your voice dies like you’ve just run out of steam.

“I bet you’ve got folders upon folders of this stuff in your secret porn hoard,” Undyne says, grin widening, and you can’t even manage a peep of protest because she’s _very, very right._ She props her face on the heel of her hand, balanced along her (lean, powerful) thigh (that is still cinched around you very invitingly). “You ever think about trying it in, like, real life?”

You gape at her for a full thirty seconds before you can manage, like an idiot, _“How?”_

Her grin widens even more—Undyne can never be out-grinned, she’ll always find a way to display more teeth more cheerfully. “Let’s just say I got a couple of ideas.”

 

 

You reconvene in the bedroom after half an hour, you needing to save your game and turn off your laptop and clean up your workspace and yourself, and Undyne seeing to whatever mysterious preparations she has in mind.

She has the bed neatly covered in towels when you arrive, you guess to minimize the eventual cleanup work—sex with her is usually pretty messy for one reason or another, after all. She’s also lounging on top of these towels in a pair of boxers and nothing else, slouched back with her stomach muscles taut because she knows _exactly_ how good she looks and loves to drive you crazy.

You feel awkward and frumpy for a minute in your anime con shirt and robot-print skirt, but, well, you _always_ feel awkward and frumpy if you start comparing yourself to Undyne in the looks department, so you just take a deep breath and pull the shirt over your head and unzip the skirt and leave them on the seat of your chair without ceremony.

“W-what d-do you want me to do?” you ask, shooting for bold and managing to hit nervous instead.

“First maybe come join me up here,” says Undyne, patting the mattress beside her.

“R-right,” you say, and half scrabble up on your own power, with Undyne supplying some extra lifting to hitch you up without dislodging the towels.

“Lemme look at you first,” she says, the minute you sit down—she doesn’t even lift her hands off your body, stroking them slowly down your sides instead. Her grin and beady one-eyed gaze are still sharp, but a little bit gentler; her hands are warm and steady and careful, and you try not to choke as you suck in a breath. “I can’t ever get over how cute and soft you are.”

Soft isn’t—generally—a word you’d apply to yourself. Chubby or round, maybe, if you’re feeling generous towards your body on a given day; porky or stumpy or just plain fat, if you’re not. But when Undyne compliments you, she calls you _squishy_ and _cuddly_ and _soft,_ like those are things she really appreciates, and Undyne doesn’t do insincerity. She values passion and stubbornness and kindness above all, so where you might give someone else a dubious look for speaking of you as _soft,_ when Undyne says it, you feel like actually that might be an okay thing to be.

“C—can I t-touch you too?” you babble.

“Sure,” she tells you. “Go ahead.”

Undyne is the furthest thing from soft, you think. She can be gentle and kind, of course, but her body is hard and scrappy and lean: She lanks and gangles and postures and brays laughter wherever she goes, strong and tough, arms strung with ropy muscle, chest and stomach flat and toned as any bishounen in your vast manga library. You run your palms down them, appreciative, liking the way her muscles shift as she breathes. She’s got sensitive gills down her sides and hidden along her jawline for when she’s underwater, but on land she processes air in her labyrinth, adapted to survive here just like you. There are scars here and there along her arms and legs and torso, artifacts of training, nothing she tries to hide, but she still keeps the black patch over her empty left eye socket.

“H—” You swallow and push on, trying not to let the immediacy of Undyne’s body intimidate you, reminding yourself of how she seems gung-ho enough, and of all the other weird kink adventures you’ve undertaken together. (Your girlfriend is into some _stuff.)_ “H-how are we going to, um, do this?”

She rises up on her knees in response, and because your arms aren’t that long, your hands sort of naturally drop to either side of her hips, thumbs on the sharp narrow bones of her pelvis.

“What _I_ was thinking was, we get this—” she gestures to her underwear here— “off, we get you laying down, we get _me_ taken care of while I’m over top of you, and see what that does to get _you_ taken care of too. That sound good?”

“Y—yeah, sure, I-I guess that w-would be easiest,” you babble, heart thumping away under your ribs at the look in her eye as she regards you. She waggles her eyebrows a little, grinning at you with her lower lip held loosely between her teeth, and you smile back (pretty daringly, you think) and hook your thumbs under the waistband of her boxers, pulling them smoothly down her thighs.

Undyne takes over from there, having to navigate her knees and shins out of her underwear, and while she’s busy with her shifting and repositioning, you take the time to get couple pillows underneath the towel carpet she laid out over the bed. This will be easier on your stomach muscles and your neck if you can have support instead of having to crane up; you lie back tentatively, squirm around so that your head and shoulders are propped up, check the towels to make sure everything’s still secured, and then squirm around even more to make sure that your tail isn’t bent at an awkward angle.

You manage to get comfy just in time, it seems, because no sooner have you settled than Undyne scoots up the bed to straddle you on her knees. She reaches out casually and gently to touch your face, and you look up at the gentleness of her expression for a moment and have to look away.

“Hi,” she says, and you snort out a quiet laugh.

“Hi,” you say back, and reach up to trace her sides, keeping your fingertips light over her gill tissue. Undyne’s body hitches a little, and she makes a quiet appreciative _mmmm_ low down in her throat, too loud for a hum but too controlled for a moan.

You stroke her stomach, her back, her ass, her thighs, leaning in to lick and kiss lightly at the joint of her legs. You can’t fit tongue or fingers into her—her body’s not built to allow penetration like yours, you’d only hurt her trying, but stimulating the outside of the small opening with very gentle kisses and touches is more than enough to get her breathing deep and rhythmic, her body swaying gently under the motions of your hands and mouth.

All the while, her hands remain steady on your shoulders, lifting now and again to brush your face in tiny caresses. It surprised you back when you first started sleeping together, the way that she’s so willing to let you do what you like with her—and only a little because in your manga and games and anime it’s more common for characters to prefer to _only_ act or _only_ receive. Undyne is just so exuberant and aggressive and noisy in day-to-day life that you’d never imagined her being able to be patient and tender this way. It’s a side of her that very few people know exists, and you feel proud to be among that number.

“Shit, Alphy, that’s really good,” she’s saying even now, and you press your feet to the towels and curl your toes in them because the roughness in her voice makes you ache for contact, and. Not yet. “Alph—”

There’s warning in her voice, and you ease your head back just a little—and she grips your shoulders hard and lets her head fall back. You see her eye close as she starts to come.

Her milt pours down across your bare chest and stomach in a deluge, in a—a _torrent,_ so much more and thicker even than the (apparently, according to your research) slightly overexaggerated amount of semen that the characters in your porn stash produce. (Of course she does, your scientist self informs you, bright and cheerful and distant: She’s built to fertilize a whole _cloud_ of eggs discharged by an aquatic or amphibious partner.) It’s hot on your scales, the scent sharp in your nose, and your face is so close to her body—you can _watch_ the flex of her gills, the minute ripples in her stomach muscles, the fluttering of the insides of her thighs, the tense and release of that little opening, and it’s all so much clearer than you just feeling it while you palm her or keep licking and kissing her through her orgasm.

All these observations are distant and strange when so much of you is preoccupied by the sensation of her come on your body—its weight, its heat, the way it drips thicker than liquid but still differently from the footage you’ve watched of semen. It runs down the curves of your body, approaching your belly and tail and the seam of your cloaca, and you’re pretty sure that if it does you’re going to come right on the spot.

“Good?” Undyne says, huffing a little. You lift your chin to see that she’s staring down at you now, apparently a little amused by your enthrallment.

“D-definitely,” you reply. “Definitely d- _definitely_ g-good.”

She rubs her thumb against your cheek, and you wish you could purr like Mew Mew instead of just sighing happily. “That’s real good,” she says, and she sounds so sincerely pleased with you and herself that you close your eyes and push your face against her hand. She keeps stroking the ridge of your cheek for another few moments, and then adds wickedly, “Time to get you cleaned up then.”

Undyne removes her hand and you open your eyes and make some eloquent noise like _buh??,_ but she’s already got one of the softer towels in her hands and is bringing it down to your milt-sticky body.

She rubs your chest down brisk and refreshing, and then her hands move down to your stomach and you gasp, then further down to between your legs and something _implodes_ down there and sends sparks all across your eyes, and you fling your head back against the pillows beneath you and yelp and thrash against her ministrations.

Undyne brings you down with softer strokes, spooling your orgasm out until you’re shuddering and too sensitive even to bear the soft press of the towel, and have to bat lightly at her hands until she gets the hint and puts it away. Your throat is dry; your brain feels fried. Aftershocks are still rushing up and down your nerves like pleasant currents.

“We’ve _got_ to come up with more ways to incorporate this boocockey stuff if it’s gonna get you this riled up _every_ time,” she proclaims, smug as the cat who got the cream, and you’re so torn between groaning and correcting her pronunciation and melting and enthusiastically agreeing that all you can do is close your eyes and laugh.


End file.
